Treatment Control

The compound, 2-methyl-1,2-bis-(3-pyridyl)-1-propanone (SU 4885) is regarded as a relative specific inhibitor of hydroxylation at C11\g=b\of the steroid nucleus (Liddle, Island, Lance & Harris, 1958). Recently, however, evidence has accumulated suggesting an inhibitory action of SU 4885 on oestrogen biosynthesis (Kahnt & Neher, 1962; Griffiths, 1963; Giles & Griffiths, 1964; F\l=o"\ldes,Koref, Feh\l=e'\r & Steczek, 1964). In the present study an attempt was made to obtain evidence for an effect of SU 4885 on oestrogen synthesis in vivo. Six female rats of the Wistar strain with a regular oestrous cycle, weighing 130\p=n-\ 170 g., were injected s.c. with 10 mg. SU 4885 as the ditartrate salt, twice daily for nine consecutive days. They all showed continuous dioestrus from the 5th to 9th day after injection, when they were killed. In another experiment four female rats of the same strain, weighing 130\p=n-\150g., were given SU 4885 orally at a daily dose of 80\p=n-\ 120 mg. for 17 consecutive days. After the 7th day of administration these animals were also in continuous dioestrus until they were killed on the 17th day. Nineteen rats of the same strain with similar body weights, killed during dioestrus were used as controls. In the SU 4885-treated rats the weight of the ovaries was increased despite a significant decrease in the weight of the uterus (Table 1) and histologically there was atrophy in the endometrium but not in the ovaries. The luteinizing hormone Table 1. Effect of SU 4885 on weight of uterus, ovaries and adrenals and on the gonadotrophin content of the rat pituitary (means ± s.e.) (Number of rats used in parentheses.